It's a point between two masses where the gravitational effects are at equilibrium (e.g. a point in space where the gravitational effects between the earth and sun are in balance). The James Webb telescope is sitting at a Lagrange point, but there are more of them. I don't know if it would matter--would putting it there keep it stable and cancel out any negative consequences for earth's orbit? I have no idea--just a thought.
This was sort of what I was getting at when I said it's sort of a three body problem. Although I realize this is beyond my area of expertise, and I concede that even beyond Earth's Hill Sphere's small changes can impact the solar system, I'm still skeptical that the planet of the size and distance the OP mentioned would be catastrophic to Earth. @Suzuzu's experiment shows mild but significant effects, but I'm wondering how long those took to happen. If that takes effect gradually over several thousands of years, then it's even more tolerable to humans.
You misunderstand me, I think - I'm not really in the market for alternative solutions. Putting a new planet into the solar system is the whole point of this concept, not an excuse for a space colony story. It's the whole idea of a mysterious alien planet appearing within our reach and we don't really know what we'll find when we go there. Terraforming Venus or Mars would be a different story. That would be the third Lagrange Point of Earth. It's a cool idea (though not at all new) but the problem is that L3 is very unstable and can't hold on to objects for long. It also couldn't be exactly opposite the Earth since this planet doesn't literally orbit around the sun, rather the Earth and sun orbit each other around a point between them, the barycenter. It's just that the sun is so much larger than Earth that the barycenter is actually inside of it.
Apparently the only stable Lagrange points are L4 and L5. Though, I'm pretty sure it only works if the objects in question are a lot smaller than the bodies keeping them there. L4 and L5 are the positions of the Earth Trojan asteroids, I believe.
Well, the physics of this is beyond me, but what if this planet was in a highly inclined orbit at the same distance as the Earth, but also in an orbital resonance such that their paths never cross? In other words, if the Earth orbits east-west around the Sun's equator (which it doesn't quite), then this planet could orbit north-south around the poles. I imagine that would pose the same physical problems as adding a counter-Earth as it exchanges energy with Venus.
Which Lagrange point? Lagrange points are stable points around a 2 body system, but if you add a planet, you’re not a 2 body system anymore and there are no Lagrange points. It’d have to be pretty far out to not affect the inner solar system, the four rocky planets’s positions are dictated by the fact that there are four of them and by the location of Jupiter. Putting a fifth object in there radically destabilizes everything. You could put a large planet further out where it’s gravity would affect us less and likely not cause too much near-term disturbance of the gas giants. In orbit around Jupiter or Saturn should work fine. The other side of earths orbit wouldn’t work either. You’re still adding mass and potential energy into the system as a whole and everything interacts with everything else. An orbit like that would never be stable. While it was fun 25 years ago to wonder if there could be a brown dwarf or another planet somewhere far out in the solar system, but today, such an object would be extremely bright in our modern instruments. There are no large bodies left to find anywhere near the sun. The biggest possible object would be smaller than the ice giants and it’d have to be deep in the keiper belt / Oort Cloud, way to far to affect us in any way.
Orientation of orbit shouldn’t matter, like you said, it’ll have the same physical pull. I’m tact, aim not sure anything could orbit in that direction without being pulled back towards the planetary plane in a few centuries by Jupiter.
I'm not misunderstanding, but if the mechanics of how it got there aren't important, why not have the new planet just suddenly replace Venus in orbit? Then there's no issues of extra mass destabilising things, and you can solve all of the other issues that would come with terraforming Venus at the same time.
I like this, too. The mass of the planet wouldn't be important, since all that mattered would be its distance from the Sun.
@Fervidor Love the question and already some great responses. In the spoiler just added the link for the Universal Sandbox also NSTMF model to play with. Spoiler Universe Sandbox NSTMF (nationalmedals.org) Solar System - Wikipedia Orbital mechanics - Wikipedia Sun - Wikipedia Lagrange point - Wikipedia Original thought was the asteroid belt was once a planet that was destroyed in the wake of the solar systems formation. This would be a neat idea as everything now is more stable. Only thing is the combined mass of the belt is a tenth that of Earth. But it’s a start… Ignoring the logistic of this… This is a struggle, but here goes. If a new planet appeared in the habitable zone with a similar mass to that of the Earth several things will start to happen, even if it’s in a stable orbit around the Sun. Our Sun is a low-mass star and contains 99.86% of the solar systems known mass and dominates it gravitationally. Of the remaining 0.14% mass, the four gas giants account for 99% of that. Leaving everything else including the inner planets with less than 0.002% of the solar systems total mass. This means adding another Earth may take our slice of mass pie up to 0.0025% at the expense of everything else. This is not much so should indicate no to little impact at all if placed in the right location and orbit as you say. Time becomes a factor here in your story. The Universe Sandbox should show a stable system going forward and this maybe the case. However, the combined gravitational mass of the Sun and the Inner planets has increased to 99.8625% of the total mass of the solar system. This would cause an ever so slight decrease in Jupiter’s orbit and so on down the line… Solar system contraction. This would take eons to be noticeable, but once noticed it will accelerate and orbits decay faster. The counter to this is the rate at which the Sun converts Hydrogen into Helium releasing energy reduces its mass. That’s a trade off from opposing time scales, which is something to explore. Next to look at is the total mass of our solar system. Itself is locked in an orbit around the Milky Way Galaxy taking about 240million years. We’ve completed about 20orbits so far. With our extra mass, even though it’s a small increase our solar system will travel slower (orbit slower). It would also attract more passing by objects into the Sun’s pull as her influence as increased marginally. These are big time-scales… Hope this helps MartinM.
In Heinlein's "Stranger in a Strange Land" the Martians destroyed a planet, which created an asteroid belt. ------- I'm just curious about how the new planet appears. Does it just pop in from nowhere, or does it sort of coast in over eons and is it captured by the sun?
Weird idea suggested by recent posts—somehow they 'clean up' the asteroid belt and put a planet in its place. Hey, I said it was a weird idea! Don't ask me how they 'clean up the asteroid belt'—maybe they get in little ships and fire lasers at individual asteroids, like in the arcade game? But I figure, if they can move a planet into plce, then this isn't all that much harder.
@Fervidor From my above post an additional Earth like planet located in the inner solar system would have a mild effect if placed correctly in an orbit. A few on the thread have said you can’t “Ignore the logistic of this, and how it got there...”. Its your story you can do what you want. I can tell you somethings about the people who placed it there if you like? Kardashev scale - Wikipedia This is a method of measuring a civilization’s level of technological advancement based on the amount of energy it is able to use. I would guess these people are a full type II civilization. They can directly consume the energy of a star. This may involve completion of a Dyson sphere. At this level of advancement, they would be able to successfully move an object with the mass of a small planet easily. Just to put things into context, we Homo Sapiens have not yet reached Type I civilization status. It was suggested that if we increase our energy consumption at an average rate of 3percent each year then in about 150years time we would have gained Type I status. Using similar rates, we would gain Type II status in about 5,000years time. And Type III could range from 100,000 to a million years. Therefore, we can quickly see how much more advanced these people are. The Pyramids in Egypt were built around 5,000 years ago. Think about our advancement in technology since then to now. Food for thought... We are just ants compared to these people. MartinM.
That is an option. Though, I may want to keep Venus around, or the aliens responsible would rather not "steal" a planet from its home system even if they leave a superior one in exchange. Besides, it doesn't really answer my original question, the point of which being that I want to determine whether or not my first idea is remotely realistic before I look for alternatives. Any idea how big of a time-scale we're talking? If it won't cause a problem for hundreds of millions of years, that would be acceptable. If its more like: "Earth will have to be vacated in a few centuries", that's quite a different cup of tea. I'm assuming it's closer to the latter, but as I've said, I don't really know much about the physics of these things. Eh, the whole thing is mainly just an idea I had that I thought would be cool and it's gone through a few iterations by now. The first idea is that a frozen-over rogue planet would drift into the solar system, settle in an orbit fairly close to the sun and then when the ice melts it reveals a bunch of alien ruins and stuff. Though, I figured this is absurdly unlikely to happen smoothly if it's even possible. So, the second version has the planet simply appear out of nowhere, already in a stable orbit. How this happens isn't terribly important since not knowing that just adds to the mystery. In the third version, there have been tensions between humanity and the aliens, and the latter offer a planet as a peace offering. Humanity accepts, thinking the aliens are just ceding territory, only for the aliens to teleport an entire planet into the solar system. Sort of like a veiled threat not to mess with them. I do know about the Kardashev scale, though I'm not sure how much it would apply to my writing. In the sci-fi setting I've been working on, I imagine that energy consumption isn't a big issue anymore. Basically, everyone has access to limitless power drawn from another dimension. Also, most advanced technology operates on principles that don't quite obey the standard laws of physics. Constructing something like a Dyson sphere (at least for the purpose of harvesting energy) probably wouldn't be a very practical use of resources. Moving a whole planet would still be very impressive, but likely for reasons other than the energy requirements. I guess one could rank civilizations depending on how much energy they are capable of producing (equivalent to a star, rather than generated by the star itself) but that has as much to do with industrial capacity as it does technological advancement. Heck, the more advanced species may actually use less energy than the others, simply because their tech is more efficient.
@Fervidor Any idea how big of a time-scale we're talking? I would guess millions of years, but have never run a model. I suggest you do this. Also look at the Sun’s burn rate. As her mass reduces, she’ll increase in size, but the orbiting planets will not be consumed just moved into ever higher/wider orbits. This due to her gravitational pull weakening with reduced mass. The numbers in years become big and hard to follow. Suggest research on the cosmic calendar. Spoiler The Cosmic Calendar | Cosmos: Possible Worlds - YouTube Cosmic Calendar - Wikipedia Then look at the Sun’s burn rate and convert it to the cosmic calendar. Probably by February year 2 we as humans need to be off Earth and away from the Solar System. Also, you can model Jupiter’s inner movement with a timeline that fits. It gives you a plausible event horizon. The first idea is that a frozen-over rogue planet would drift into the solar system, settle in an orbit fairly close to the sun and then when the ice melts it reveals a bunch of alien ruins and stuff. Though, I figured this is absurdly unlikely to happen smoothly if it's even possible. If the Aliens were a Type II, then yes, I could fully believe they could achieve this without much disturbance to the solar system. RESEARCH The hunt for Planet9. Orbital mechanics needs a look. I do know about the Kardashev scale, though I'm not sure how much it would apply to my writing. In the sci-fi setting I've been working on, I imagine that energy consumption isn't a big issue anymore. Basically, everyone has access to limitless power drawn from another dimension. I think an understanding of mass-energy equivalence is probably needed. Using another dimension won’t solve your problems, but make for a cheap sci-fi trope. READ The Three Body Problem by Liu Cixin. Hope this helps MartinM.
So, does that mean it is possible to just drop a planet into the system with no issues? I dunno, I just assume that pushing it into the solar system from the outside would be much harder than just teleporting it into its proper position. Like, you're going to have to run the math anyway, right? Oh, I have nothing against cheap sci-fi tropes. If anything, I thrive on them. Do elaborate on what you mean by mass-energy equivalence, however. What problems would I be facing? I know about that one, but everything I've heard about it suggests it's too depressing for my taste. Honesty, I'm just trying to create a sci-fi setting full of hope and wonder and borderline magic. But I like to have a reasonably realistic basis for my ridiculous space magic if at all possible.
@Fervidor So, does that mean it is possible to just drop a planet into the system with no issues? I dunno, I just assume that pushing it into the solar system from the outside would be much harder than just teleporting it into its proper position. Like, you're going to have to run the math anyway, right? Its your story you do what you like with it. Orbital Mechanics could make a predictable path for the planet to slowly follow. Remember the mass talk earlier? To simply drop a planet into position no issues I could think of a way. A highly advanced race could possibly fold the planet into a higher dimension. The Race then travel to the orbit position and reverse the process. They don’t carry/transport the planet they just unfold it from a higher dimensional plane. Oh, I have nothing against cheap sci-fi tropes. Totally agree and it is your story. I know about that one, but everything I've heard about it suggests it's too depressing for my taste. The Aliens in the trilogy do something similar with dimensional space. It is worth a look, and by far the best Sci-Fi series I’ve ever read. Yes, can be a tad dark. MartinM.
Something that might be less disruptive could be if this planet settled into a binary orbit with another planet. You can see something like this with Pluto and its moon Charon, where they're close enough in mass that they orbit a point in empty space, and eternally face towards each other.
@Naomasa298 It's still adding mass, and transfer of energy into a system. You are absolutely correct, but read my earlier posts here. The overall mass of an earth sized rocky planet adds little to the overall solar system. If the planet came in at an oblique angle towards the inner core with little velocity it could find a stable orbit with little disruption. To your point, its increase in mass added to the Sun and inner 4 planets would tug Jupiter inward over time. Also, the Solar System as a whole would slow fractionally, orbiting the Milky Way slower, even been pulled closer to the galactic center. The magnitudes of time scales though are vast and maybe balanced out by the Sun losing notable mass burning off Hydrogen into Helium. MartinM.
